QLayout: add a way to unset user-defined contents margins

Once user-defined margins are set on a layout, there's no way
to unset them, except by abusing setContentsMargins and passing
-1, which is a total API abuse (does a negative margin mean that
contents *overflow* the layout?). Add a proper function.

[ChangeLog][QtWidgets][QLayout] Added unsetContentsMargins().

Change-Id: I089788a7470f9649a8f00e42914dafb7242f12cd
Reviewed-by: Samuel Gaist <samuel.gaist@idiap.ch>

2 files changed, 14 insertions, 0 deletions

diff --git a/src/widgets/kernel/qlayout.cpp b/src/widgets/kernel/qlayout.cpp
index db7aa1aaeb..39c7f7ec3f 100644
--- a/src/widgets/kernel/qlayout.cpp
+++ b/src/widgets/kernel/qlayout.cpp
@@ -353,6 +353,19 @@ void QLayout::setContentsMargins(const QMargins &margins)
 }
 
 /*!
+    \since 6.1
+
+    Unsets any user-defined margins around the layout. The layout will
+    use the default values provided by the style.
+
+    \sa setContentsMargins()
+*/
+void QLayout::unsetContentsMargins()
+{
+    setContentsMargins(-1, -1, -1, -1);
+}
+
+/*!
     \since 4.3
 
     For each of \a left, \a top, \a right and \a bottom that is not
diff --git a/src/widgets/kernel/qlayout.h b/src/widgets/kernel/qlayout.h
index 0377aa62b3..4686a999a5 100644
--- a/src/widgets/kernel/qlayout.h
+++ b/src/widgets/kernel/qlayout.h
@@ -85,6 +85,7 @@ public:
 
     void setContentsMargins(int left, int top, int right, int bottom);
     void setContentsMargins(const QMargins &margins);
+    void unsetContentsMargins();
     void getContentsMargins(int *left, int *top, int *right, int *bottom) const;
     QMargins contentsMargins() const;
     QRect contentsRect() const;